Biotransformation and removal of heavy metals: a review of phytoremediation and microbial remediation assessment on contaminated soil

Abstract

Environmental deterioration is caused by a variety of pollutants; however, heavy metals are often a major issue. Development and globalization has now also resulted in such pollution occurring in developing societies, including Africa and Asia. This review explores the geographical outlook of soil pollution with heavy metals. Various approaches used to remedy metal-polluted soils include physical, chemical, and biological systems, but many of these methods are not economically viable, and they do not ensure restoration without residual effects. This review evaluates the diverse use of plants and microbes in biotransformation and removal of heavy metals from contaminated soil. Mechanisms on how natural processes utilizing plants (phytoremediation) and microorganisms (bioremediation) remove or reduce heavy metals from soil at various levels are presented. This review concludes that remediation technologies are necessary for the recovery of metal-contaminated environments and the prevention of continuous environmentally toxic impacts on living organisms.

An operon consisting of a P-type ATPase gene and a transcriptional regular gene given the different cadmium resistances in Bacillus vietamensis 151-6 and Bacillus marisflavi 151-25

“…Plasmid elimination was performed using SDS, as previously described (El-Mansi et al 2000), with some modifications. Specifically, B. vietamensis 151-6 and B. marisflavi 151-25 were treated with 0.0005% and 0.002% SDS, respectively.…”

“…Many remediation techniques, such as chemical immobilization, electrokinetic extraction, phytoremediation, and bioremediation, have been proposed for soils contaminated with heavy metals (Liu et al 2018). Among these technologies, bioremediation is considered an innovative and promising remediation method based on its cost effectiveness and low environmental impact (Emenike et al 2018;Jacob et al 2018;Peng et al 2018). To use microorganisms to remediate heavy metal contamination, in particular Cd-contaminated soil, it is first necessary to isolate bacteria that are resistant to Cd. Many organisms have developed strategies to withstand the presence of Cd in the environment, such as exclusion, compartmentalization, deployment of inorganic polyphosphates, cell wall binding, and expression of metal binding proteins (Abbas et al 2018;Gillan 2016;Kulakovskaya 2018;Reddy et al 2016;Yu et al 2018).…”

An operon consisting of a P-type ATPase gene and a transcriptional regulator gene responsible for cadmium resistances in Bacillus vietamensis 151–6 and Bacillus marisflavi 151–25

“…Many remediation techniques, such as chemical immobilization, electrokinetic extraction, phytoremediation, and bioremediation, have been proposed for soils contaminated with heavy metals [8]. Among these technologies, bioremediation is considered an innovative and promising remediation method based on its cost effectiveness and low environmental impact [9][10][11].…”

Bioremediation of Fe, Zn and Cd ions from aqueous solution using died cells of cyanobacterial mats from extreme habitat, Siwa Oasis, Egypt.

“…Trace elements especially which have toxic effects still exist in the ecosystem and inevitably appear at wide concentrations ranges. These metals tended to accumulate and its excess concentration results an environmental contamination problems (Emenike et al, 2018). The increasing of the anthropogenic activities leads to consequence release of these metals to the surrounding environment.…”